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United States Patent |
5,257,288
|
Moser
|
October 26, 1993
|
Data transmission system
Abstract
A data transmission system and method in which digitalized information is
transmitted via a data transmission link in complete binary words from a
transmitter to a receiver. For data transmission, a complete binary word
with a defined total bit number is subdivided into one or more partial
binary words, with the respective bit numbers of the partial binary words
being variable. The individual partial binary words are allocated all
binary bit sequences that can be formed with the total number bits of the
respective partial binary words, the various bit sequences being coded at
respectively different positions within a partial binary word In each
partial binary word exactly one binary bit sequence is transmitted from
the transmitter to the receiver.
Inventors:
|
Moser; Helmut (Heilbronn, DE)
|
Assignee:
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Telefunken electronic GmbH (Heilbronn, DE)
|
Appl. No.:
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682233 |
Filed:
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April 9, 1991 |
Foreign Application Priority Data
Current U.S. Class: |
375/242; 341/53; 370/205; 375/239 |
Intern'l Class: |
H04B 014/04 |
Field of Search: |
375/21,22,23,25,113
370/8,9,10
341/53
381/52
|
References Cited
U.S. Patent Documents
3528011 | Sep., 1970 | Anderson | 375/22.
|
4866737 | Sep., 1989 | Seifried | 375/22.
|
Foreign Patent Documents |
3717886 | Dec., 1988 | DE.
| |
Other References
Jahn, W. S.: "Elektrisch Messen, . . . "; R. Pflaum Verlag Munchen, 1964;
s. 51-53.
|
Primary Examiner: Kuntz; Curtis
Assistant Examiner: Ghebretinsae; T.
Attorney, Agent or Firm: Spencer, Frank & Schneider
Claims
What is claimed is:
1. In a data transmission system in which digitalized information is
transmitted via a data transmission link in complete binary words from a
transmitter to a receiver; the improvement wherein said transmitter
includes means for subdividing a complete binary word with a defined total
bit number into one or more partial binary words, with the bit number of
the respective said partial binary words being variable; means for
storing, for each individual partial binary word, all binary bit sequences
that can be formed with the total number of bits of the respective partial
binary word, and with the various bit sequences being coded at
respectively different positions within a respective partial binary word;
and means for transmitting to said receiver, in each partial binary word,
a signal corresponding to the coded position of exactly one binary bit
sequence indicative of the information to be transmitted.
2. A data transmission system in accordance with claim 1, wherein said
means for transmitting includes means for emitting, in each partial binary
word, a transmission pulse for a position bit in the form of a rectangular
pulse at that position of the respective partial binary word at which the
binary bit sequence to be transmitted is coded; and wherein the receiver
includes means for allocating said transmission pulse to that binary bit
sequence corresponding to the position of said transmission pulse within
the respective partial binary word.
3. A data transmission system in accordance with claim 2, wherein the
receiver further includes means for combining the binary bit sequences
corresponding to the transmission pulses in the individual partial binary
words into a complete binary word, and a decoder for emitting an output
signal corresponding to the transmitted information.
4. A data transmission system in accordance with claim 1, wherein said
means for subdividing the complete binary words with a certain total bit
number into the individual partial binary words and the respective bit
number of said partial binary words prior to data transmission comprises a
computer that also controls the time coordination between the transmitter
and the receiver.
5. In a data transmission method including transmitting digitalized
information via a data transmission link in complete binary words from a
transmitter to a receiver; the improvement wherein said step of
transmitting includes: subdividing a complete binary word with a defined
total bit number into one or more partial binary words, with the bit
number of said partial binary words being variable; allocating to the
individual partial binary words, all binary bit sequences that can be
formed with the total number of bits of each respective partial binary
word; coding the various said bit sequences at respectively different
positions within a respective partial binary word; and in each partial
binary word, transmitting exactly one binary bit, corresponding in
position to the coded bit sequence, from the transmitter to the receiver.
6. A data transmission method in accordance with claim 5, wherein said step
of transmitting one binary bit includes emitting in each partial binary
word, a transmission pulse for a position bit in the form of a rectangular
pulse at that position of the respective partial binary word at which the
binary bit sequence to be transmitted is coded; and further comprising the
steps of receiving the transmission pulse in the receiver and allocating
said transmission pulse to that binary bit sequence corresponding to the
position of said transmission pulse in the respective partial binary word.
7. A data transmission method in accordance with claim 6, further
comprising the step of combining the binary bit sequences corresponding to
the transmission pulses in the individual partial binary words received in
the receiver into a complete binary word, and emitting an output signal
corresponding to the transmitted information.
8. A data transmission method in accordance with claim 5, wherein said step
of subdividing the complete binary words with a certain total bit number
into the individual partial binary words and the respective bit number of
said partial binary words are determined prior to data transmission by a
computer that also controls the time coordination between the transmitter
and the receiver.
9. A data transmission method in accordance with claim 6, further
comprising controlling the timing of the data transmission in the receiver
by time counters integrated in a receiver computer.
10. A data transmission method in accordance with claim 9, wherein said
step of controlling the timing includes using a first time counter
(Z.sub.1) to mark the position of the position bit pulses in the
individual partial binary words.
11. A data transmission method in accordance with claim 9, wherein said
step of controlling includes using a second time counter (Z.sub.2) to
monitor the pulse width (t.sub.p) of the position bit pulses.
12. A data transmission method in accordance with claim 6, further
comprising emitting a start bit pulse in the form of a rectangular pulse
before the first position bit pulse of the first partial binary word.
13. A data transmission method in accordance with claim 6, wherein said
step of transmitting further includes emitting, after the position bit
pulse of the last partial binary word, an additional position bit pulse
for a check partial binary word used to very the code of the information
previously transmitted.
14. A data transmission method in accordance with claim 13, wherein the
position bit pulse in said check partial binary word is always emitted at
the same position in said check partial binary word and is therefore
always allocated the same binary bit sequence in the receiver.
15. A data transmission method in accordance with claim 13, further
comprising determining the position of the position bit pulse in the check
partial binary word by parity formation or addition of the previously
transmitted binary bit sequences of the complete binary word.
16. A data transmission method in accordance with claim 12, wherein said
step of transmitting further comprises emitting an auxiliary bit pulse
before the start bit pulse; and starting data transmission only when the
time (t) between the auxiliary bit pulses and the start bit pulse is
inside a time interval predetermined by a time counter (Z.sub.3).
17. A data transmission method in accordance with claim 16, further
comprising determining a pulse width (t.sub.s) of the start bit pulse by a
second time counter (Z.sub.2) and starting data transmission only when
said pulse width (t.sub.s) is inside a certain predetermined time
interval.
18. A data transmission method in accordance with claim 6, wherein the
position bit pulses have different characteristics depending on the
respective partial binary word and/or on the position within said partial
binary word.
19. A data transmission method in accordance with claim 18, wherein the
position bit pulses have alternating characteristics in consecutive
partial binary words.
20. A data transmission method in accordance with claim 18, wherein the
position bit pulses have alternating characteristics in consecutive
positions within the partial binary words.
21. A data transmission method in accordance with claim 18, wherein the
pulse width of the position bit pulses is varied.
22. A data transmission method in accordance with claim 18, wherein the
pulse duration of the position bit pulses is selected differently in order
to vary the pulse width.
23. A data transmission method in accordance with claim 21, wherein the
number of oscillation periods of a modulation frequency is selected
differently in order to vary the pulse width of the position bit pulses.
24. A data transmission method in accordance with claim 18, wherein the
frequency of the position bit pulses is varied.
25. A data transmission method in accordance with claim 24, wherein two
different frequencies (f.sub.1, f.sub.2) are selected.
Description
DESCRIPTION OF THE PRIOR ART
The invention relates to a data transmission system of the type wherein
digitalized information is transmitted via a data transmission link in
complete binary words from a transmitter to a receiver.
Data transmission systems in digital technology transmit information in the
form of digitalized data packets via a data transmission link between a
transmitter and a receiver The data can be transmitted in, for example,
the infrared range, the radio frequency range or the ultrasonic range
using the appropriate suitable transmitter equipment, receiver equipment
and transmission links. The digitalized data packets or binary sequences,
the so-called binary words, are transmitted here in the form of
rectangular pulses.
In standard data transmission systems, a transmission pulse is required for
each digitalized information unit to be output or transmitted to the
receiver --i.e., for each bit emitted by the transmitter. To code the two
different information units "0" and "1" of the binary code, the pulses are
either emitted at different times within a determined time interval, for
example, by means of pulse interval modulation, or modulated using
different frequencies.
Since a pulse has to be emitted for every bit transmitted by the
transmitter, the energy requirement for the data transmission is quite
high on the transmitter side. In addition, dependability is not especially
high with this data transmission mode; to improve this, expensive
measures, for example duplicate transmission of the information with
subsequent comparison, are required.
SUMMARY OF THE INVENTION
The object underlying the invention is to provide a new transmission
principle for a data transmission system in which the energy requirement
on the transmitter side can be reduced and the dependability improved.
The above object generally is achieved in accordance with the invention by
a data transmission system or method in which digitalized information is
transmitted via a data transmission link in complete binary words from a
transmitter to a receiver and wherein: for data transmission, a complete
binary word with a defined total number of bits is subdivided into one or
more partial binary words, with the number of bits of the partial binary
words being variable; each individual partial binary word is allocated all
binary bit sequences that can be formed with the total number of bits of
the respective partial binary word; the respective various bit sequences
are coded at respectively different positions within a partial binary
word; and in each partial binary word, exactly one binary bit sequence is
transmitted from the transmitter to the receiver.
More particularly and preferably, the binary bit sequences are transmitted
such that in each partial binary word from the transmitter, a transmission
pulse for a position bit is emitted in the form of a rectangular pulse at
that position of the respective partial binary word at which the binary
bit sequence to be transmitted (and corresponding to the partial binary
word) is coded, and the receiver allocates the transmission pulse to that
binary bit sequence corresponding to the position of the transmission
pulse.
In accordance with the invention, the complete binary word is divided up
into one or more partial binary words with variable bit number, the number
of the partial binary words and the number of bits per partial binary word
being permanently set for a certain bit number of the complete binary
word, preferably by means of a computer.
Each partial binary word is allocated a certain number of positions
--dependent on the bit number of the partial binary word each of which
code for certain bit sequences; this coding can differ for the various
partial binary words.
For data transmission, a transmission pulse is emitted--after emission of a
start bit pulse--by the transmitter at a certain position within each
partial binary word; this position bit pulse is detected by the receiver
and the bit sequence corresponding to the respective position is
allocated. The transmitted bit sequences of the individual partial binary
words are combined into a complete binary word; this emits, after decoding
of the complete binary word, an output signal corresponding to the
transmitted information.
Since in accordance with the invention a single transmission pulse emitted
by the transmitter--that for the position bit--already codes, for a
partial binary word, a bit sequence of several bits and not only for a
single bit, far fewer transmission pulses are necessary for transmission
of an n-bit complete binary word instead of n-transmission pulses; the
energy requirement for the transmitter can therefore be considerably
reduced. The division of the complete binary word into partial binary
words, i.e. the number of partial binary words and their respective bit
number, can be optimized to suit the total bit number of the complete
binary word to be transmitted in order to achieve a minimum energy
requirement and transmission expenditure. This division or allocation is
preferably permanently preset by a computer that also controls the timing
in the transmitter and receiver as well as the coordination between the
transmitter and the receiver.
The reduction of the pulses necessary for data transmission brings not only
a reduction in the energy requirement, but also a substantial improvement
in dependability. In addition, the position bit pulses can be given,
depending on the respective partial binary word or on the position within
a partial binary word, a different characteristic. Since, the receiver
must recognize and verify this characteristic, the dependability can
thereby be further increased. A better error evaluation can, for example,
be achieved when the pulse width of the position bit pulses is varied
between even and uneven in consecutive partial binary words or within a
partial binary word as a function of the position. The differing pulse
width can be set by variation of the pulse duration or, if the pulses are
modulated with a certain frequency, by variation of the number of
oscillation periods. Alternatively to variation of the pulse width, the
oscillation frequency with which the transmission pulses are modulated can
also be varied.
Additionally or alternatively to the change in the characteristic of the
transmission pulses, it is possible to emit an additive auxiliary bit
pulse--which does not itself code for information --before the start pulse
bit; data transmission by means of the position bit pulses or evaluation
by the receiver is only started when the auxiliary bit pulse has been
transmitted from the transmitter to the receiver at a certain time,
previously set before the start bit pulse.
Thanks to the low energy requirement for the data transmission system in
accordance with the invention, an additional check partial binary word
following on from the last partial binary word of the complete binary word
can be transmitted as a further check mechanism and to verify the code of
the last information transmitted. In this check partial binary word, a
position bit pulse is for example always emitted at a predetermined
position of the partial binary word, or parity formation or addition on
the basis of the previously transmitted bit sequences of the individual
partial binary words is performed. This permits easy recognition of
transmission errors, and the usual duplicate transmission of information
for error recognition can be dispensed with.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in greater detail below on the basis of FIGS. 1
to 3.
Here,
FIG. 1 is the layout in diagram form of a data transmission system,
FIG. 2 shows the coding principle of an n-bit binary word, and
FIG. 3 shows the time sequence for data transmission in the case of a
16-bit binary word.
DESCRIPTION OF A PREFERRED EMBODIMENT
In accordance with FIG. 1, the data transmission system is made up of the
transmitter 1, the transmission link 2 and the receiver 3.
The transmitter 1 predetermines, codes and emits at the transmitter output
the information to be transmitted. In FIG. 1, the information is converted
into a complete binary word, after key A, B, C etc. of keyboard 10 is
pressed, by the transmitter computer 11, which comprises, for example, the
transmitter unit 12 proper and the keyboard encoder 13. The keyboard
encoder 13 is a control logic unit for processing the transmission signal
and for regulating the timimg of the transmitter signal, for example for
subdividing the complete binary word into the various partial binary words
and for providing the various transmission pulses 21. The driver 14, for
example a power amplifier, passes the transmission pulses 21 to the
transmission link 2. Data can be transmitted via the data transmission
link 2 in, for example, the infrared range, the radio frequency range or
the ultrasonic range without carrier or via fixed wires/lines. The
characteristic sequence of transmission pulses 21 emitted by the
transmitter when the keyboard 10 is operated, for example, by pressing a
certain key A, B, C, . . . , is evaluated by the receiver 3, by the
receiver detecting the transmitted pulse sequence, decoding it, and then
emitting an output signal characteristic for the pressed key of the
transmitter 1. For this purpose, the receiver 3 has a converter 30 that
converts the transmission pulses 21 into an electrical signal, a
pre-amplifier 31 that can have, for example, two selective inputs for
distinguishing two different frequencies f.sub.1 and f.sub.2, a receiver
computer 32 comprising a counter unit 33 with the time counters Z.sub.1 to
Z.sub.3, and a decoding unit 34 with the switch 35. The decoded signal is,
for example as a HIGH or LOW logic level, emitted to one of the lines A,
B, C, . . . allocated to the appropriate pressed key.
In the case of a data transmission system in the IR range, for example, in
an IR remote control, IR transmission pulses 21 are emitted by the driver
14, which comprises for example a transistor and an IR transmitter diode,
and are modulated with a frequency of 40 kHz, for example. The IR
transmitter signal thus modulated is converted in the converter 30, for
example an IR receiver diode, into a voltage or current. The pre-amplifier
31 contains an integrator that smoothes the modulated signal and supplies
it to the receiver computer 32. A switching module controlled depending on
the key pressed is connected to the receiver output, for example.
The coding principle of the transmission pulses used for data transmission
is shown in diagram form in FIG. 2. The complete binary word is subdivided
into several partial binary words; FIG. 2 shows three partial binary
words, with the first partial binary word 1 having m-bits, the second
partial binary word 2 m'-bits and the partial binary word 3 m"-bits. The
number of positions n (n', n") within the partial binary words is given by
the relationship n=2.sup.m ; i.e. the first partial binary word has
2.sup.m, the second partial binary word 2.sup.m', the third partial binary
word 2.sup.m" positions. Different partial binary words can have different
bit numbers m, m', m" and therefore a different number of positions n, n',
n". Each position within a partial binary word codes for a certain bit
sequence with m (m', m") bits, so that in each partial binary word all bit
combinations that can be formed with the bits of the partial binary word
are allocated to the different positions. The division of the complete
binary word into the partial binary words, the number of bits per partial
binary word and the allocation of the respective positions to the
corresponding bit sequences are determined before data transmission and
filed in a memory. This determination process can, for a certain bit
number of the complete binary word, be achieved either by hardware with
hard wiring, or by software, for example using a microprocessor. This
subdivision or allocation can be selected for high flexibility, with
different bit sequences being allocated to the same position in different
partial binary words.
Within each partial binary word, the bit sequence coded at the respective
position is allocated by the position bit pulse output by the transmitter
at a position 1 . . . n (n', n") to this partial binary word in the
receiver. In accordance with FIG. 2, for example, the position bit pulse
is output at position 2 in the partial binary word 1 and the binary bit
sequence 10000 . . . effectively is transmitted, in partial binary word 2
the position bit pulse is output at position 4 and the binary bit sequence
11000 . . . effectively is transmitted etc.
The principle and the timing of the data transmission is illustrated in
using FIG. 3 using the example of a 16-bit complete binary word.
The 16-bit complete binary word to be transmitted, for example the bit
sequence 1010110010011100 in accordance with FIG. 3, is split up into 4
equal partial binary words of 4 bits each prior to transmission, so that
each partial binary word has 2.sup.4 =16 positions 1 to 16. Depending on
which position 1 to 16 the position bit pulse is output at by the
transmitter, this pulse is allocated a 4-bit sequence 0000 to 1111 in the
receiver as a function of the position. FIG. 3 the same position/bit
sequence allocation was selected for all 4 partial binary words 1 to 4.
For the 16-bit complete binary word to be transmitted, it is necessary,
for example in accordance with the subdivision into 4 equal partial binary
words as selected above, that the position corresponding bit pulses be at
position 6 (bit sequence 1010) in partial binary word 1, at position 4
(corresponding bit sequence 1100) in partial binary word 2, at position 10
(corresponding sequence 1001) in partial binary word and at position 4
(corresponding bit sequence 1100) in partial binary word 4. In the
receiver, reception of the transmitted start bit pulse is followed by
starting of the time counter Z.sub.1, which, knowing the length of the
respective partial binary words, i.e. the number of positions, monitors
the timing within the partial binary words. The counter Z.sub.1 therefore
marks and determines the position within the partial binary words, at
which-position the position bit pulse was emitted by the transmitter. When
the first position bit pulse has been recognized, it is allocated the
first 4-bit partial binary word 1010 by the receiver, after recognition of
the second position bit pulse the second 4-bit partial binary word 1100
etc. After the last 4-bit partial binary word 4 (1100) has been recognized
by the receiver, the bit sequences of the various partial binary words are
combined into the complete binary word, and after decoding of the complete
binary word, an output signal is emitted. The time cycle can now begin at
the start, i.e. the receiver is ready to receive a new complete binary
word. The further complete binary word can represent a repetition of the
transmitted information, for example by lengthy pressing of one key of the
transmitter, or new information, for example by pressing a different key
of the transmitter. The time counter Z.sub.1 is re-initialized at the
start of transmission of the new complete binary word, for example by the
microprocessor.
To detect errors and as a means of checking the data transmission, a
further time counter Z.sub.2 is provided that monitors the pulse width
t.sub.s of the start bit pulse and of the position bit pulses t.sub.p. For
example, even/uneven positions--as shown for the partial binary word 3 in
accordance with FIG. 3, or consecutive partial binary words--as shown in
FIG. 3 for the partial binary words 1 and 2--can be allocated different
pulse widths of the transmission pulses. This can be achieved by, for
example, a variation in the pulse duration or, in the case of modulated
transmission pulses, by a different number of oscillation periods of the
modulation frequency. With a faulty pulse width, there is no evaluation of
the transmission signal on the receiver side.
Instead of varying the pulse width t.sub.p, the various emitted position
bit pulses can be allocated different modulation frequencies. This is
shown as an example in FIG. 3 for the two frequencies f.sub.1 and f.sub.2
in the partial binary word 4, where the frequency is varied even/uneven
depending on the position.
Error recognition is also given, i.e. the evaluation of the transmission
signal is likewise not started on the receiver side, --when the time t
between the auxiliary bit pulse and the start bit pulse is not inside a
previously determined time interval or window. The time t is monitored by
a further time counter Z.sub.3. Thanks to these error recognition methods
or check mechanisms, it is possible to ensure a very dependable data
transmission in addition to reducing the energy requirement. This permits
duplicate binary word transmissions with subsequent binary word
comparisons as normally applied, for example, in infrared
transmissions--to be dispensed with.
The data transmission system in accordance with the invention can be used,
for example for infrared remote control of television or in automobiles
for opening and closing of doors etc.
Transmission systems in the radio frequency range or in other wavelength
ranges of the electro-magnetic spectrum are also conceivable.
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